Kinematic Self-Replicating Machines

© 2004 Robert A. Freitas Jr. and Ralph C. Merkle. All Rights Reserved.

Robert A. Freitas Jr., Ralph C. Merkle, Kinematic Self-Replicating Machines, Landes Bioscience, Georgetown, TX, 2004.


6.5 Focusing on Molecular Assemblers

According to Merkle [3104], the broad goals of nanotechnology – the ability to inexpensively arrange atoms in most of the ways permitted by physical law – are now widely accepted. But it is not enough to agree that heavier than air flight is possible, nor is it sufficient to believe that some as-yet unspecified design based on rockets can reach the moon, nor does the abstract realization that mass can be converted to energy change the course of history. We need to move to the next step: the Wright brothers, the Apollo Program, the Manhattan Project. We need to translate abstract agreement into a focused and well-funded project.

Nanosystems [208] gave us a persuasive feasibility argument for assemblers, but provided no design for a specific assembler. For every fundamental design problem, Nanosystems [208] gave us several feasible solutions – but never picked one specific solution. Indeed, one of the main conclusions of this work was that we could have confidence that assemblers were feasible precisely because there were many solutions to every problem. While it is difficult to be absolutely certain that a specific solution will work, when there are many possible solutions available it’s almost certain that at least one of them will work.

We’ve seen continued work on specific aspects of assembler design but we haven’t seen a complete design. Such a design (and accompanying analysis) is feasible today, but a complete design will require the work of a coordinated team of people for some years. We need to explore the space of possible designs, analyze at least some designs in full detail, and then use those designs as a focal point for further development. We could start today, but as yet, we have not.

The major consequence of this failure is continuing delay, much of which will be caused by a persistent confusion about “what is an assembler.” While we are encouraged that all the fundamental problems can be solved, we don’t yet have a single design or preferred embodiment that selects a specific solution for each problem and integrates those specific solutions into a single unified system for more rigorous analytical testing. Perhaps more seriously, there is the fog and uncertainty created by mental confusion and misunderstanding. People have a hard time grasping complex arguments and abstract conclusions, and when we are hearing new ideas for the first time it’s very easy to get confused. For instance, flight to the moon was once thought to be impossible because “there is no air to push against” in the vacuum of space. The reasoning: Airplane wings push against air, propellers push against air, helicopter blades push against air – so surely the proposed space rockets were meant to push against air? But there is no air in space! Thus can our experience with familiar things mislead us when we consider fundamentally new ideas.

A project with many people must have a clear, detailed, and comprehensive description of both the goal and how to achieve it. We need at least one design for an assembler with all the kinks worked out, all the irritating little design issues settled, all the potential sticking points resolved. Without this, any effort to build an assembler will deteriorate into chaos and confusion as the people involved find themselves working at cross purposes – possibly without even realizing it. For example, if we started out to build a heavier-than-air flying machine lacking a complete plan, and one person designs the blades for a helicopter while another works out the wings of an airplane and a third person analyzes propelling the device by throwing sticks of dynamite out the rear and exploding them, the result will be chaos.

Right now, the detail that we can achieve in a system design is limited by the fact that serious analytical efforts have so far been restricted to small teams of one or a few people. We could significantly increase the detail of the design by increasing the number of people working on it, provided they are the right people. A dozen people, properly coordinated, could start to provide us with coherent system designs having a level of detail that would give us greater collective clarity in understanding the goal and a greater ability to determine the developmental pathways for reaching it.

Besides pursuing designs in more depth and detail, we should also examine systems that differ radically in their approach and assumptions. We can explore the design space (Section 5.1.9) seeking designs that are, for example, easier to build. Consider again the case of the Analytical Engine, designed by Babbage in the 1830s (Section 6.3.4). Although it was the conceptual foundation for the single most important technological development of the 20th century (programmable digital computers), Babbage’s design was never built nor was there any systematic exploration of possible alternatives. Looking back with the advantage of perfect hindsight, we can clearly see what Babbage and the rest of the world missed: electromechanical relays. Relays were known in the 1830s and were widely employed during the 1840s in telegraphy. Had Babbage and others systematically surveyed the complete design space for “Analytical Engines,” they might have realized that a relay-based computer would be relatively easy to build and quite practical. But they didn’t, and so they missed an opportunity of historic magnitude – as did the rest of humanity, who lost the benefits of an earlier implementation of digital computers.

Let’s not miss another opportunity.


Last updated on 1 August 2005